The fate of the language was influenced by the increasing power of the English state in Ireland. Elizabethan officials viewed the use of Irish unfavourably, as being a threat to all things English in Ireland. Its decline began under English rule in the seventeenth century. In the latter part of the nineteenth century there was a dramatic decrease in the number of speakers, beginning after the Great Famine of 1845–52 (when Ireland lost 20–25% of its population either to emigration or death). Irish-speaking areas were hit especially hard. By the end of British rule, the language was spoken by less than 15% of the national population.[9] Since then, Irish speakers have been in the minority. This is now the case even in areas officially designated as the Gaeltacht. Efforts have been made by the state, individuals and organisations to preserve, promote and revive the language, but with mixed results.

Around the turn of the 21st century, estimates of native speakers ranged from 20,000 to 80,000 people.[10][11][12] In the 2006 census for the Republic, 85,000 people reported using Irish as a daily language outside of the education system, and 1.2 million reported using it at least occasionally in or out of school.[13] In the 2011 Census, these numbers had increased to 94,000 and 1.3 million, respectively.[14] There are several thousand Irish speakers in Northern Ireland. It has been estimated that the active Irish-language scene probably comprises 5 to 10 per cent of Ireland's population.[15]

In recent decades there has been a significant increase in the number of urban Irish speakers, particularly in Dublin. This community, described as disparate but large, well-educated and mostly middle-class, enjoys a lively cultural life, and has been linked to the growth of non-mainstream schools which teach through the medium of Irish.[16]

There are also many Irish speakers abroad, particularly in the United States and Canada. Irish was spoken until the early twentieth century on the island of Newfoundland, in a form known as Newfoundland Irish.

In An Caighdeán Oifigiúil (the official written standard) the name of the language is Gaeilge (Irish pronunciation: [ˈɡeːlʲɟə]). Before the spelling reform of 1948, this form was spelled Gaedhilge; originally this was the genitive of Gaedhealg, the form used in classical Modern Irish.[17] Older spellings of this include Gaoidhealg in Classical Irish [ge:ʝəlˠg] and Goídelc [goiðelˠg] in Old Irish. The modern spelling results from the deletion of the silent dh in the middle of Gaedhilge, whereas the name Goidelic language, used to refer to the language family including Irish, comes from Old Irish.

Other forms of the name found in the various modern Irish dialects (in addition to south Connacht Gaeilge above) include Gaedhilic/Gaeilic/Gaeilig ([ˈɡeːlʲɪc]) or Gaedhlag ([ˈɡeːl̪ˠəɡ]) in Ulster Irish and northern Connacht Irish and Gaedhealaing/Gaoluinn/Gaelainn ([ˈɡˠeːl̪ˠɪŋʲ/ˈɡˠeːl̪ˠɪnʲ])[18][19] in Munster Irish.

In Europe the language is usually referred to as Irish, with Gaelic or "Irish Gaelic" used in some instances elsewhere.[20] The term Irish Gaelic is often used when English speakers discuss the relationship between the three Goidelic languages (Irish, Scottish Gaelic, and Manx). Sometimes "Irish" is taken to mean Hiberno-English, a form of English associated with Ireland. Scottish Gaelic is usually referred to simply as Gaelic, though pronounced differently ([ˈkaːlikʲ]listen(help·info)).

Written Irish is first attested in Ogham inscriptions from the fourth century AD; this stage of the language is known as Primitive Irish. These writings have been found throughout Ireland and the west coast of Great Britain. Primitive Irish transitioned into Old Irish through the 5th century. Old Irish, dating from the sixth century, used the Latin alphabet and is attested primarily in marginalia to Latin manuscripts. During this time, the Irish language absorbed many Latin words, including ecclesiastical terms: examples are easpag (bishop) from episcopus, and Domhnach (Sunday, from dominica). By the 10th century, Old Irish had evolved into Middle Irish, which was spoken throughout Ireland and in Scotland and the Isle of Man. It is the language of a large corpus of literature, including the Ulster Cycle. From the 12th century Middle Irish began to evolve into modern Irish in Ireland, into Scottish Gaelic in Scotland, and into the Manx language in the Isle of Man. Early Modern Irish, dating from the thirteenth century, was the basis of the literary language of both Ireland and Gaelic-speaking Scotland. Modern Irish, as attested in the work of such writers as Geoffrey Keating, may be said to date from the seventeenth century, and was the medium of popular literature from that time on.

From the eighteenth century on, the language lost ground in the east of the country, partly because the British government discouraged its use in education, law and administration, partly because of the spread of bilingualism – a conspicuous example of the process known by linguists as language shift.[21] It was a change characterised by diglossia (two languages being used by the same community in different social and economic situations) and transitional bilingualism (monoglot Irish-speaking grandparents with bilingual children and monoglot English-speaking grandchildren). By the mid-eighteenth century English was becoming a language of the Catholic middle class, the Catholic Church and public intellectuals, especially in the east of the country. English had a particular economic value for emigrants, especially females. Increasingly, as the value of English became apparent, the prohibition on Irish in schools had the sanction of parents.[22] The Great Famine (1845–1849) is seen as precipitating the final catastrophic decline.

It has been argued, however, that Irish was not marginal to Ireland’s modernization in the nineteenth century, as often assumed, but was in fact central to it. Irish speakers insisted on using the language in the law courts (even when they knew English). Irish was an urban as well as a rural language and was commonly used in commercial transactions. The language was heavily implicated in the "devotional revolution" which marked the standardisation of Catholic religious practice. It was also widely used in a political context. Down to the time of the Great Famine and even after it, the language was in use by all classes, including the well-to-do and those in professional occupations.[23]

This linguistic dynamism has been linked to the efforts of certain public intellectuals to counter the decline of the language. At the end of the nineteenth century they instituted the Gaelic Revival in an attempt to encourage the learning and use of Irish, though few adult learners mastered the language.[24] The vehicle of the revival was the Gaelic League, and particular emphasis was placed on the folk tradition, which in Irish is particularly rich. Efforts were also made to develop journalism and a modern literature.

Irish is given recognition by the Constitution of Ireland as the national and first official language of the Republic of Ireland (with English being another official language). Although this is technically the case, in practice almost all government debates and business are conducted in English.[25] In 1938, the founder of Conradh na Gaeilge (The Gaelic League), Douglas Hyde, was inaugurated as the first President of Ireland. The record of his delivering his inaugural Declaration of Office in Roscommon Irish remains almost the only surviving remnant of anyone speaking in that dialect.

Though the First Official Language requirement was also dropped for wider public service jobs, Irish remains a required subject of study in all schools within the Republic which receive public money (see also Education in the Republic of Ireland). Those wishing to teach in primary schools in the State must also pass a compulsory examination called "Scrúdú Cáilíochta sa Ghaeilge". The need for a pass in Leaving Certificate Irish or English for entry to the Gardaí (police) was introduced in September 2005, although applicants are given lessons in the language during the two years of training. The most important official documents of the Irish Government must be published in both Irish and English or Irish alone (in accordance with the Official Languages Act 2003, enforced by "An Coimisinéir Teanga", the Irish language ombudsman).

The National University of Ireland requires all students wishing to embark on a degree course in the NUI federal system to pass the subject of Irish in the Leaving Certificate or GCE/GCSE Examinations.[27] Exemptions are made from this requirement for students born outside of the Republic of Ireland, those who were born in the Republic but completed primary education outside it, and students diagnosed with dyslexia.

The National University of Ireland, Galway is required to appoint people who are competent in the Irish language, as long as they are also competent in all other aspects of the vacancy they are appointed to. This requirement is laid down by the University College Galway Act, 1929 (Section 3).[28] It is expected that the requirement may be repealed in due course.[29]

For a number of years there has been vigorous debate in political, academic and other circles about the failure of most students in the mainstream (English-medium) schools to achieve competence in the language, even after fourteen years.[30][31][32] The concomitant decline in the number of traditional native speakers has also been a cause of great concern.[33][34][35][36] In 2007, filmmaker Manchán Magan found few speakers and some incredulity while speaking only Irish in Dublin. He was unable to accomplish some everyday tasks, as portrayed in his documentary No Béarla.[37]

There is, however, a growing body of Irish speakers in the cities. Most of these are products of an independent education system in which Irish is the sole language of instruction. Such schools are known at the primary level as Gaelscoileanna and are supported by a number of secondary colleges. These Irish-medium schools send a much higher proportion of students on to tertiary level than do the mainstream schools, and it seems increasingly likely that, within a generation, habitual users of Irish will typically be members of an urban, middle-class and highly educated minority.[38]

Parliamentary legislation is supposed to be available in both Irish and English but is frequently only available in English. This is notwithstanding that Article 25.4 of the Constitution of Ireland requires that an "official translation" of any law in one official language be provided immediately in the other official language—if not already passed in both official languages.[39]

There are parts of Ireland where Irish is still spoken daily to some extent as a traditional native language. These regions are known individually and collectively as the Gaeltacht, or in the plural as Gaeltachtaí. While the Gaeltacht's fluent Irish speakers, whose numbers have been estimated at twenty or thirty thousand,[40] are a minority of the total number of fluent Irish speakers, they represent a higher concentration of Irish speakers than other parts of the country and it is only in Gaeltacht areas that Irish continues to be a natural community vernacular for part of the general population.

The percentage of respondents who said they spoke Irish daily outside the education system in the 2011 census in Ireland.

According to data compiled by the Irish Department of Community, Rural and Gaeltacht Affairs, only one quarter of households in officially Gaeltacht areas are fluent in Irish. The author of a detailed analysis of the survey, Donncha Ó hÉallaithe of the Galway-Mayo Institute of Technology, described the Irish language policy followed by Irish governments as a "complete and absolute disaster". The Irish Times, referring to his analysis published in the Irish-language newspaper Foinse, quoted him as follows: "It is an absolute indictment of successive Irish Governments that at the foundation of the Irish State there were 250,000 fluent Irish speakers living in Irish-speaking or semi Irish-speaking areas, but the number now is between 20,000 and 30,000".[40]

In the 1920s, when the Irish Free State was founded, Irish was still a vernacular in the following areas: south Connemara, from a point west of Spiddal, covering Inverin, Carraroe, Rosmuck, and the islands; the Aran Islands; northwest Donegal in the area around Gweedore, including Rannafast (Rann na Feirste, birthplace of notable writers and musicians); Gortahork, the surrounding townlands and Tory Island; the townland of Rathcarn, County Meath.[41] To some extent this remains the case. The strongest Gaeltacht areas, numerically and socially, are those of South Connemara, the west of the Dingle Peninsula and northwest Donegal, in which some residents still use Irish as their primary language. These areas were referred to until recently as the Fíor-Ghaeltacht ("true Gaeltacht").

Irish summer colleges are attended by tens of thousands of Irish teenagers annually. Students live with Gaeltacht families, attend classes, participate in sports, go to céilithe and are obliged to speak Irish. All aspects of Irish culture and tradition are encouraged.

A sign for the Department of Culture, Arts and Leisure in Northern Ireland, in English, Irish, and Ulster Scots.

Before the establishment of the Northern Ireland state in 1921, Irish was recognised as a school subject and as "Celtic" in some third level institutions. Between 1921 and 1972, Northern Ireland had devolved government. During those years the political party holding power in the Stormont Parliament, the Ulster Unionist Party (UUP), was hostile to the language. The context of this hostility was the political use of the language by Nationalists to assert the belief of an Independent Ireland.[42] In broadcasting, there was an exclusion on the reporting of minority cultural issues, and Irish was excluded from radio and television for almost the first fifty years of the previous devolved government.[43] The language received a degree of formal recognition in Northern Ireland from the United Kingdom, under the 1998 Good Friday Agreement,[44] and then, in 2003, by the Government's ratification in respect of the language of the European Charter for Regional or Minority Languages. The British government promised to create legislation encouraging the language as part of the 2006 St Andrews Agreement.[45]

Irish became an official language of the EU on 1 January 2007 meaning that MEPs with Irish fluency can now speak the language in the EU Parliament in Europe and at committees although in the case of the latter they have to give prior notice to a simultaneous interpreter in order to ensure that what they say can be interpreted into other languages. While an official language of the European Union, only co-decision regulations must be available in Irish for the moment, due to a renewable five-year derogation on what has to be translated, requested by the Irish Government when negotiating the language's new official status. Any expansion in the range of documents to be translated will depend on the results of the first five-year review and on whether the Irish authorities decide to seek an extension. The Irish government has committed itself to train the necessary number of translators and interpreters and to bear the related costs.[46]

Before Irish became an official language it was afforded the status of treaty language and only the highest-level documents of the EU had been made available in Irish.

The Irish language was carried abroad in the modern period by a vast diaspora, chiefly to Britain and North America, but also to Australia, New Zealand and Argentina. The first large movements began in the 17th century, largely as a result of the Cromwellian conquest, which saw many Irish sent to the West Indies. Irish emigration to America was well established by the 18th century, and was reinforced in the 1840s by thousands fleeing from the Famine. This flight also affected Britain. Up until that time most emigrants spoke Irish as their first language, though English was steadily establishing itself as the primary language. Irish speakers had first arrived in Australia in the late 18th century as convicts and soldiers, and many Irish-speaking settlers followed, particularly in the 1860s. New Zealand also received some of this influx. Argentina was the only non-English speaking country to receive large numbers of Irish emigrants, and there were few Irish speakers among them.

Relatively few of the emigrants were literate in Irish, but manuscripts in the language were brought to both Australia and America, and it was in America that the first newspaper to make significant use of Irish was established. In Australia, too, the language found its way into print. The Gaelic Revival, which started in Ireland in the 1890s, found a response abroad, with branches of the Gaelic League being established in all the countries to which Irish speakers had emigrated.

The decline of Irish in Ireland and a slowing of emigration helped to ensure a decline in the language abroad, along with natural attrition in the host countries. Despite this, a handful of enthusiasts continued to learn and cultivate Irish in diaspora countries and elsewhere, a trend which strengthened in the second half of the 20th century. Today the language is taught at tertiary level in North America, Australia and Europe, and Irish speakers outside Ireland contribute to journalism and literature in the language. There are significant Irish-speaking communities in the United States and Canada;[47] figures released for the period 2006-2008 show that 22,279 Americans spoke Irish at home.[48]

The Irish language is also one of the Official languages of the Celtic League (political organisation) which is a non-governmental organisation that promotes self-determination and Celtic identity and culture in Ireland, Scotland, Wales, Brittany, Cornwall and the Isle of Man, known as the Celtic nations. It places particular emphasis on the indigenous Celtic languages. It is recognised by the United Nations as a non-governmental organisation with "Roster Status" and is part of the UN's Economic and Social Council. The organisation has branches in all the Celtic Nations and in Patagonia, Argentina, New York City, US, and London, UK.

Of the 1.77 million who indicated they could speak Irish, 77,185 said they speak it daily outside the education system. A further 110,642 said they spoke it weekly, while 613,236 said they spoke it less often. One in four said they never spoke Irish.

The numbers speaking Irish on a daily basis outside the education system showed an increase of 5,037 since 2006, from 72,148 to 77,185; the numbers of weekly speakers showed an increase of 7,781 persons, while those speaking Irish less often showed the largest increase of 27,139.

To place those figures in context, the same report provided statistics for other household languages in Ireland (excluding English).

Irish is represented by several traditional dialects and by various varieties of "urban" Irish, or better school Irish, the latter being English-influenced regional or standard Irish. Differences between the dialects make themselves felt in stress, intonation, vocabulary and structural features.

Roughly speaking, the three major dialect areas which survive coincide with the provinces of Munster (Cúige Mumhan), Connacht (Cúige Chonnacht) and Ulster (Cúige Uladh). Records of some dialects of Leinster were made by the Irish Folklore Commission and others prior to their extinction. Newfoundland, in eastern Canada, had a form of Irish derived from the Munster Irish of the later eighteenth century (see Newfoundland Irish).

Down to the early nineteenth century (and often later) Irish was spoken in all the counties of Leinster: Carlow, Dublin, Kildare, Kilkenny, Laois, Longford, Louth, Meath, Westmeath, Offaly, Wexford and Wicklow. The evidence furnished by placenames, literary sources and recorded speech indicates that there were three dialects spoken in Leinster: one main dialect and two of lesser significance. The minor dialects were represented by the Ulster speech of counties Meath and Louth, which extended as far south as the Boyne valley, and a Munster dialect found in Kilkenny and south Laois. The main dialect was represented by a broad central belt stretching from west Connacht eastwards to the Liffey estuary and southwards to Wexford, though with many local variations.

As the main dialect was of the Connacht type, it typically placed the stress on the first syllable of a word. Another Connacht characteristic, found in placenames, was a preference for the pronunciation cr where the standard spelling is cn. The word cnoc (hill) would therefore be pronounced croc. Examples are the placenames Crooksling (Cnoc Slinne) in County Dublin and Crukeen (Cnoicín) in Carlow. East Leinster showed the same diphthongisation or vowel lengthening as in Munster and Connacht Irish in words like poll (hole), cill (monastery), coill (wood), ceann (head), cam (crooked) and dream (crowd). A feature of the dialect was the pronunciation of the vowel ao, which generally became ae in east Leinster (as in Munster), and í in the west (as in Western Irish).[50]

Early evidence regarding colloquial Irish in east Leinster is found in The Fyrst Boke of the Introduction of Knowledge (1547), by the English physician and traveller Andrew Borde.[51] The illustrative phrases he uses include the following (with regularised Irish spelling in brackets):

The Pale (An Pháil) was an area around late medieval Dublin under the control of the English government. By the late 15th century it consisted of an area along the coast from Dalkey, south of Dublin, to the garrison town of Dundalk, with an inland boundary encompassing Naas and Leixlip in the Earldom of Kildare, and Trim and Kells in County Meath to the North. Into this area of "Englyshe tunge" the Irish language steadily advanced. An English official remarked of the Pale in 1515 that "all the common people of the said half counties that obeyeth the King's laws, for the most part be of Irish birth, of Irish habit, and of Irish language".[52]

With the strengthening of English cultural and political control, language reversal began to occur, but this did not become clearly evident until the eighteenth century. Even then, in the decennial period 1771–1781, the percentage of Irish speakers in Meath was at least 41%. By 1851 this had fallen to less than 3%.[53]

English expanded strongly in Leinster in the eighteenth century, but Irish speakers were still numerous. In the decennial period 1771-1781 certain counties had estimated percentages of Irish speakers as follows (though the estimates are likely to be too low):[53]

Kilkenny 57%

Louth 57%

Longford 22%

Westmeath 17%

The language saw its most rapid initial decline in Laois, Wexford, Wicklow, County Dublin and perhaps Kildare. The proportion of Irish-speaking children in Leinster went down as follows: 17% in the 1700's, 11% in the 1800's, 3% in the 1830's and none in the 1860's.[54]

The Irish census of 1851 showed that there were still a number of older speakers in County Dublin.[53] Sound recordings were made between 1928 and 1931 of some of the last speakers in Omeath, County Louth (now available in digital form).[55] The last known traditional native speaker in Omeath, and in Leinster as a whole, was Annie O'Hanlon (née Dobbin), who died in 1960.[22]

Munster Irish is mainly spoken in the Gaeltacht areas of Kerry (Contae Chiarraí), Ring (An Rinn) near Dungarvan (Dún Garbháin) in Waterford (Contae Phort Láirge) and Muskerry (Múscraí) and Cape Clear Island (Oileán Chléire) in the western part of Cork (Contae Chorcaí). The most important subdivision in Munster is that between Decies Irish (Na Déise) (spoken in Waterford) and the rest of Munster Irish.

Some typical features of Munster Irish are:

The use of endings to show person on verbs in parallel with a pronominal subject system, thus "I must" is in Munster caithfead as well as caithfidh mé, while other dialects prefer caithfidh mé (mé means "I"). "I was and you were" is Bhíos agus bhís as well as Bhí mé agus bhí tú in Munster, but more commonly Bhí mé agus bhí tú in other dialects. Note that these are strong tendencies, and the personal forms Bhíos etc. are used in the West and North, particularly when the words are last in the clause.

Use of independent/dependent forms of verbs that are not included in the Standard. For example, "I see" in Munster is chím, which is the independent form – Northern Irish also uses a similar form, tchím), whereas "I do not see" is ní fheicim, feicim being the dependent form, which is used after particles such as ní "not"). Chím is replaced by feicim in the Standard. Similarly, the traditional form preserved in Munster bheirim I give/ní thugaim is tugaim/ní thugaim in the Standard; gheibhim I get/ní bhfaighim is faighim/ní bhfaighim.

When before -nn, -m, -rr, -rd, -ll and so on, in monosyllabic words and in the stressed syllable of multisyllabic words where the syllable is followed by a consonant, some short vowels are lengthened while others are diphthongised, thus ceann[kʲaun] "head", cam[kɑum] "crooked", gearr[ɡʲaːr] "short", ord[oːrd] "sledgehammer", gall[ɡɑul] "foreigner, non-Gael", iontas[uːntəs] "a wonder, a marvel", compánach[kəumˈpɑːnəx] "companion, mate", etc.

A copular construction involving ea "it" is frequently used. Thus "I am an Irish person" can be said is Éireannach mé and Éireannach is ea mé in Munster; there is a subtle difference in meaning, however, the first choice being a simple statement of fact, while the second brings emphasis onto the word Éireannach. In effect the construction is a type of "fronting".

Both masculine and feminine words are subject to lenition after insan (sa/san) "in the", den "of the" and don "to/for the" : sa tsiopa, "in the shop", compared to the Standard sa siopa (the Standard lenites only feminine nouns in the dative in these cases).

Eclipsis of f after sa: sa bhfeirm, "in the farm", instead of san fheirm.

Eclipsis of t and d after preposition + singular article, with all prepositions except after insan, den and don: ar an dtigh "on the house", ag an ndoras "at the door".

Stress falls in general found on the second syllable of a word when the first syllable contains a short vowel, and the second syllable contains a long vowel, diphthong, or is -(e)ach, e.g. biorán ("pin"), as opposed to biorán in Connacht and Ulster.

Historically, Connacht Irish represents the westernmost remnant of a dialect area which stretched across the centre of Ireland to the east coast. The strongest dialect of Connacht Irish is to be found in Connemara and the Aran Islands. Much closer to the larger Connacht Gaeltacht is the dialect spoken in the smaller region on the border between Galway (Gaillimh) and Mayo (Maigh Eo). The northern Mayo dialect of Erris (Iorras) and Achill (Acaill) is in grammar and morphology essentially a Connacht dialect, but shows some similarities to Ulster Irish due to large-scale immigration of dispossessed people following the Plantation of Ulster though it is this form of Irish which is closest to the true original Connacht dialect which would have been spoken in Counties Sligo, Roscommon, Leitrim and East Galway.

Features in Connacht Irish differing from the official standard include a preference for verbal nouns ending in -achan, e.g. lagachan instead of lagú, "weakening". The non-standard pronunciation of the Cois Fharraige area with lengthened vowels and heavily reduced endings gives it a distinct sound. Distinguishing features of Connacht and Ulster dialect include the pronunciation of word final broad bh and mh as [w], rather than as [vˠ] in Munster. For example sliabh ("mountain") is pronounced [ʃlʲiəw] in Connacht and Ulster as opposed to [ʃlʲiəβ] in the south. In addition Connacht and Ulster speakers tend to include the "we" pronoun rather than use the standard compound form used in Munster e.g. bhí muid is used for "we were" instead of bhíomar.

As in Munster Irish, some short vowels are lengthened and others diphthongised before -nn, -m, -rr, -rd, -ll, in monosyllabic words and in the stressed syllable of multisyllabic words where the syllable is followed by a consonant. This can be seen in ceann [kʲɑ:n] "head", cam [kɑ:m] "crooked", gearr [gʲɑ:r] "short", ord [ourd] "sledgehammer", gall [gɑ:l] "foreigner, non-Gael", iontas [i:ntəs] "a wonder, a marvel", etc. The form '-aibh', when occurring at the end of words like 'agaibh', tends to be pronounced as an 'ee' sound.

There are a number of differences between the popular South Connemara form of Irish, the Mid-Connacht/Joyce Country form (on the border between Mayo and Galway), and the Achill and Erris forms in the north of the province.

In South Connemara, for example, there is an tendency to substitute a "b" sound at the end of words ending in "bh" [β], such as sibh, libh and dóibh, something not found in the rest of Connacht (these words would be pronounced respectively as "shiv," "liv" and "dófa" in the other areas). This placing of the B-sound is also present at the end of words ending in vowels, such as acu (pronounced as "acub") and leo (pronounced as "lyohab"). There is also a tendency to omit the "g" sound in words such as agam, agat and againn, a characteristic also of other Connacht dialects. All these pronunciations are distinctively regional.

The pronunciation prevalent in the Joyce Country (the area around Loch Corrib and Loch Mask) is quite similar to that of South Connemara, with a similar approach to the words agam, agat and againn and a similar approach to pronunciation of vowels and consonants. But there are noticeable differences in vocabulary, with certain words such as doiligh (difficult) and foscailte being preferred to the more usual deacair and oscailte. Another interesting aspect of this sub-dialect is that almost all vowels at the end of words tend to be pronounced as í: eile (other), cosa (feet) and déanta (done) tend to be pronounced as eilí, cosaí and déantaí respectively.

The Irish of Achill and Erris tends to differ from that of South Connacht in many aspects of vocabulary and, in some instances, of pronunciation. It is often stated that the Irish of these regions has much in common with Ulster Irish, with words ending -mh and -bh having a much softer sound, with a tendency to terminate words such as leo and dóibh with "f", giving leofa and dófa respectively. In addition to a vocabulary typical of other area of Connacht, one also finds words like amharc (meaning "to look" and pronounced "onk"), nimhneach (painful or sore), druid (close), mothaigh (hear), doiligh (difficult), úr (new), and tig le (to be able to - i.e. a form similar to féidir).

Ulster Irish sounds very different and shares several features with southern dialects of Scottish Gaelic and Manx Gaelic, as well as having lots of characteristic words and shades of meanings. However, since the demise of those Irish dialects spoken natively in what is today Northern Ireland, it is probably an exaggeration to see present-day Ulster Irish as an intermediary form between Scottish Gaelic and the southern and western dialects of Irish. Northern Scottish Gaelic has many non-Ulster features in common with Munster Irish.

One noticeable trait of Ulster Irish, Manx Gaelic and Scots Gaelic is the use of the negative particle cha(n) in place of the Munster and Connacht ní. Though southern Ulster Irish tends to use ní more than cha(n), cha(n) has almost ousted ní in northernmost dialects (e.g. Rosguill and Tory Island), though even in these areas níl "is not" is more common than chan fhuil or cha bhfuil.[57][58]

Another noticeable trait is the pronunciation of the first person singular verb ending -im as -am, also common to Ulster, Man and Scotland (Munster/Connacht/Leinster siúlaim "I walk", Ulster siúlam).

Irish was spoken as a community language in Irish towns and cities up to the nineteenth century. In the sixteenth and seventeenth centuries it was widespread even in Dublin and the Pale.[59] .

The Irish of Dublin, situated as it was between the east Ulster dialect of Meath and Louth to the north and the Leinster-Connacht dialect further south, may have reflected the characteristics of both in phonology and grammar. In County Dublin itself the general rule was to place the stress on the initial vowel of words. With time it appears that the forms of the dative case took over the other case endings in the plural (a tendency found to a lesser extent in other dialects). In a letter written in Dublin in 1691 we find such examples as the following: gnóthuimh (accusative case, the standard form being gnóthaí), tíorthuibh (accusative case, the standard form being tíortha), and leithscéalaibh (genitive case, the standard form being leithscéalta).[60]

English authorities of the Cromwellian period, aware that Irish was widely spoken in Dublin, arranged for its official use. In 1655 several local dignitaries were ordered to oversee a lecture in Irish to be given in Dublin. In March 1656 a converted Catholic priest, Séamas Corcy, was appointed to preach in Irish at Bride’s parish every Sunday, and was also ordered to preach at Drogheda and Athy.[61] In 1657 the English colonists in Dublin presented a petition to the Municipal Council complaining that in Dublin itself "there is Irish commonly and usually spoken".[62]

There is contemporary evidence of the use of Irish in other urban areas at the time. In 1657 it was found necessary to have an Oath of Abjuration (rejecting the authority of the Pope) read in Irish in Cork so that people could understand it.[63]

Irish was sufficiently strong in early eighteenth century Dublin to be the language of a coterie of poets and scribes led by Seán and Tadhg Ó Neachtain, both poets of note.[64] Scribal activity in Irish persisted in Dublin right through the eighteenth century. An outstanding example was Muiris Ó Gormáin (Maurice Gorman), a prolific producer of manuscripts who advertised his services (in English) in Faulkner’s Dublin Journal.[65]

In other urban centres the descendants of medieval Anglo-Norman settlers, the so-called Old English, were Irish-speaking or bilingual by the sixteenth century.[66] The English administrator and traveller Fynes Moryson, writing in the last years of the sixteenth century, said that "the English Irish and the very citizens (excepting those of Dublin where the lord deputy resides) though they could speak English as well as we, yet commonly speak Irish among themselves, and were hardly induced by our familiar conversation to speak English with us".[67] The demise of native cultural institutions in the seventeenth century saw the social prestige of Irish diminish, and the gradual Anglicisation of the middle classes followed.[68]

The census of 1851 showed that the towns and cities of Munster still had significant Irish-speaking populations. In 1819 James McQuige, a veteran Methodist lay preacher in Irish, wrote: "In some of the largest southern towns, Cork, Kinsale, and even the Protestant town of Bandon, provisions are sold in the markets, and cried in the streets, in Irish".[69] Irish speakers constituted over 40% of the population of Cork even in 1851.[53]

The nineteenth century saw a reduction in the number of Dublin’s Irish speakers, in keeping with the trend elsewhere. This continued until the end of the century, when the Gaelic Revival saw the creation of a strong Irish–speaking network, typically united by various branches of the Gaelic League, and accompanied by renewed literary activity.[70] By the 1930s Dublin had a lively literary life in Irish.[71]

Urban Irish has been the beneficiary, over the last few decades, of a rapidly expanding independent school system, known generally as Gaelscoileanna. These schools teach entirely through Irish, and there are over thirty in Dublin alone.

It is likely that the number of urban native speakers (i.e. people who were born into Irish-speaking households and educated through Irish) is on the increase. It has been suggested that Ireland’s towns and cities are acquiring a critical mass of Irish speakers, reflected in the expansion of Irish-language media.[72] Colloquial urban Irish is changing in unforeseen ways, with attention being drawn to the rapid loss of consonantal mutations (which are intrinsic to the language). It is presently uncertain whether the urban Irish of non-native speakers will become a dialect in its own right or grow further apart from native Gaeltacht Irish and become a creole (i.e. a new language).[72]

An Caighdeán Oifigiúil ("The Official Standard"), often shortened to An Caighdeán, is the standard language, which is taught in most schools in Ireland, though with strong influences from local dialects. It was published by the translators in Dáil Éireann in the 1950s.[73]

Its development in the 1950s and 1960s had two purposes. One was to simplify Irish spelling, which had retained its Classical spelling, by removing many silent letters, and to give a standard written form that was mutually intelligible by speakers with different dialects.[73] Though many aspects of the Caighdeán are essentially those of Connacht Irish, this was simply because this is the central dialect which forms a "bridge", as it were, between the North and South. In reality, dialect speakers pronounce words as in their own dialect, as the spelling simply reflects the pronunciation of Classical Irish. For example, ceann "head" in early modern Irish was pronounced [kʲenːˠ]. The spelling has been retained, but the word is variously pronounced [kʲaunˠ] in the South, [kʲɑːnˠ] in Connacht, and [kʲænːˠ] in the North. Beag "small" was [bʲɛɡˠ] in early modern Irish, and is now [bʲɛɡˠ] in Waterford Irish, [bʲɔɡˠ] in Cork-Kerry Irish, varies between [bʲɔɡˠ] and [bʲæɡˠ] in the West, and is [bʲœɡˠ] in the North.

The simplification was weighted in favour of the Western dialect. For example, the early modern Irish leaba, dative case leabaidh[lʲebʷɨʝ] "bed" is pronounced [lʲabʷə] as well as [lʲabʷɨɡʲ] in Waterford Irish, [lʲabʷɨɡʲ] in Cork-Kerry Irish, [lʲæbʷə] in Connacht Irish ([lʲæːbʷə] in Cois Fharraige Irish), and [lʲæbʷi] in the North. Native speakers from the North and South may consider that leabaidh should be the representation in the Caighdeán rather than actual leaba. However, leaba is the historically correct nominative form and arguably preferable to the historically incorrect yet common use of the dative form for the nominative.

On the other hand, in some cases the Caighdeán retained classical spellings even when none of the dialects had retained the corresponding pronunciation. For example, it has retained the Classical Irish spelling of ar "on, for, etc." and ag "at, by, of, etc.". The first is pronounced [ɛɾʲ] throughout the Goidelic-speaking world (and is written er in Manx, and air in Scottish Gaelic), and should be written either eir or oir in Irish. The second is pronounced [iɡʲ] in the South, and [eɡʲ] in the North and West. Again, Manx and Scottish Gaelic reflect this pronunciation much more clearly than Irish does (Manx ec, Scottish aig).

In many cases, however, the Caighdeán can only refer to the Classical language, in that every dialect is different, as happens in the personal forms of ag "at, by, of, etc."

Another purpose was to create a grammatically regularised or "simplified" standard which would make the language more accessible for the majority English speaking school population. In part this is why the Caighdeán is not universally respected by native speakers, in that it makes simplified language an ideal, rather than the ideal that native speakers traditionally had of their dialects (or of the Classical dialect if they had knowledge of that). Of course, this was not the original aim of the developers, who rather saw the "school-version" Caighdeán as a means of easing second-language learners into the task of learning "full" Irish. The Caighdeán verb system is a prime example, with the reduction in irregular verb forms and personal forms of the verb – except for the first persons. However, once the word "standard" becomes used, the forms represented as "standard" take on a power of their own, and therefore the ultimate goal has become forgotten in many circles.

The Caighdeán, in general is used by non-native speakers, frequently from the capital, and is sometimes also called "Dublin Irish" or "Urban Irish". As it is taught in many Irish-Language schools (where Irish is the main, or sometimes only, medium of instruction), it is also sometimes called "Gaelscoil Irish". The so-called "Belfast Irish", spoken in that city's Gaeltacht Quarter is the Caighdeán heavily influenced by Ulster Irish and Belfast English.

The differences between dialects are considerable, and have led to recurrent difficulties in defining standard Irish. In recent decades contacts between speakers of different dialects have become more frequent and the differences between the dialects are less noticeable.[74]

As of August 2012,[75] the first major revision of the Caighdeán Oifigiúil is available, both online[76] and in print.[77] Among the changes to be found in the revised version are, for example, various attempts to bring the recommendations of the Caighdeán closer to the spoken dialect of Gaeltacht speakers,[78] including allowing further use of the nominative case where the genitive would historically have been found.[79]

In pronunciation, Irish most closely resembles its nearest relatives, Scottish Gaelic and Manx. One notable feature is that consonants (except /h/) come in pairs, one "broad" (velarised, pronounced with the back of the tongue pulled back towards the soft palate) and one "slender" (palatalised, pronounced with the middle of the tongue pushed up towards the hard palate). While broad–slender pairs are not unique to Irish (being found, for example, in Russian), in Irish they have a grammatical function and can pose a problem for English speakers.

The grammar of Irish shares with other Celtic languages a number of features which, while not unique, are unusual in an Indo-European context. The grammatical features most unfamiliar to English speakers of the language are the initial consonant mutations, the verb–subject–object (VSO) word order, and the use of two different forms for "to be".

Irish is a VSO (verb–subject–object) language, and uses two verbs of "to be". One of these, the copula (known in Irish as an chopail), is used to describe the permanent identity or characteristic of a person or thing as opposed to temporary aspects.

The adjective normally follows the noun (the possessive adjectives are an exception), but there are a certain number of adjectives and particles which may function as prefixes.

Irish is an inflected language, having, in its standard form, the following cases: common (the old nominative and accusative), vocative and genitive. In Munster dialects a dative form persisted, though this has been largely discarded by younger speakers.[81] The present inflectional system represents a radical simplification of the grammar of Old Irish.

Irish nouns may be masculine or feminine (the neuter having disappeared). To a certain degree the gender difference is indicated by specific word endings, -án and -ín being masculine and -óg feminine.

Another feature of Irish grammar that is shared with other Celtic languages is the use of prepositional pronouns (forainmneacha réamhfhoclacha), which are essentially conjugated prepositions. For example, the word for "at" is ag, which in the first person singular becomes agam "at me". When used with the verb bí ("to be") ag indicates possession; this is the equivalent of the English verb "to have".

Tá leabhar agam. "I have a book." (Literally, "there is a book at me.")

Irish shares with other Celtic languages a feature known as mutation, whereby initial and final consonants may change to express nuances of grammatical relationship and meaning. Mutation affects verbs, nouns and adjectives. Certain consonants may be capable of changing in two ways, depending on the context.

Lenition (in Irish, séimhiú "softening") describes the change of stops into fricatives. Indicated in old orthography by a buailte (a dot) written above the changed consonant (as in the dot shown above the c in "Gaelac" below), this is now shown in writing by adding an -h:

caith! "throw!" – chaith mé "I threw" (this is an example of the lenition as a past-tense marker, which is caused by the use of do, although it is now usually omitted)

margadh "market", "market-place", "bargain" – Tadhg an mhargaidh "the man of the street" (word for word "Tadhg of the market-place"; here we see the lenition marking the genitive case of a masculine noun)

Seán "Seán, John" – a Sheáin! "O John!" (here we see lenition as part of what is called the vocative case – in fact, the vocative lenition is triggered by the a or vocative marker before Sheáin)

Eclipsis (in Irish, urú) covers the voicing of voiceless stops, as well as the nasalisation of voiced stops.

athair "father" – ár nAthair "our Father"

tús "start", ar dtús "at the start"

Gaillimh "Galway" – i nGaillimh "in Galway"

Mutations are often the only way to distinguish similar grammatical forms. For example, the only way (apart from context) in which the possessive pronouns "her," "his" and "their" can be distinguished is through initial mutations, since all these meanings are represented by the same word a. It is seen here in apposition to the word bróg (shoe):

Modern Irish traditionally used the ISO basic Latin alphabet without the letters j, k, q, w, x, y and z, but with the addition of one diacritic sign, the acute accent (á é í ó ú), known in Irish as the síneadh fada "long mark", plural sínte fada. However, some gaelicised words use those letters: for instance, 'Jeep' is written as 'Jíp'. (The letter v has been naturalised into the language, although it is not part of the traditional alphabet, and has the same pronunciation as "bh".) In idiomatic English usage, this diacritic is frequently referred to simply as the fada, where the adjective is used as a noun. The fada serves to lengthen the sound of the vowels and in some cases also changes their quality. For example, in Munster Irish (Kerry), a is /a/ or /ɑ/ and á is /ɑː/ in "father" but in Ulster Irish (Donegal), á tends to be /æː/.

Traditional orthography had an additional diacritic – a dot over some consonants to indicate lenition. In modern Irish, the letter h suffixed to a consonant indicates that the consonant is lenited. Thus, for example, 'Gaelaċ' [see illustration] has become 'Gaelach'.

Around the time of World War II, Séamas Daltún, in charge of Rannóg an Aistriúcháin (the official translations department of the Irish government), issued his own guidelines about how to standardise Irish spelling and grammar. This de facto standard was subsequently approved by the State and called the Official Standard or Caighdeán Oifigiúil. It simplified and standardised the orthography. Many words had silent letters removed and vowel combination brought closer to the spoken language. Where multiple versions existed in different dialects for the same word, one or more were selected.

The standard spelling does not necessarily reflect the pronunciation used in particular dialects. For example, in standard Irish, bia, "food", has the genitive bia. In Munster Irish, however, the genitive is pronounced /bʲiːɟ/.[82] For this reason, the spelling biadh is still used by the speakers of some dialects, in particular those that show a meaningful and audible difference between biadh (nominative case) and bídh (genitive case) "of food, food's". In Munster the latter spelling regularly produces the pronunciation /bʲiːɟ/ because final -idh, -igh regularly delenites to -ig in Munster pronunciation. Another example would be the word crua, meaning "hard". This pronounced /kruəɟ/[83] in Munster, in line with the pre-Caighdeán spelling, cruaidh. In Munster, ao is pronounced /eː/ and aoi pronounced /iː/,[84] but the new spellings of saoghal, "life, world", genitive: saoghail, have become saol, genitive saoil. This produces irregularities in the match-up between the spelling and pronunciation in Munster, because the word is pronounced /sˠeːl̪ˠ/, genitive /sˠeːlʲ/.[85]

The dot-above diacritic, called a ponc séimhithe or sí buailte (often shortened to buailte), derives from the punctum delens used in medieval manuscripts to indicate deletion, similar to crossing out unwanted words in handwriting today. From this usage it was used to indicate the lenition of s (from /s/ to /h/) and f (from /f/ to zero) in Old Irish texts.

Lenition of c, p, and t was indicated by placing the letter h after the affected consonant; lenition of other sounds was left unmarked. Later both methods were extended to be indicators of lenition of any sound except l and n, and two competing systems were used: lenition could be marked by a buailte or by a postposed h. Eventually, use of the buailte predominated when texts were written using Gaelic letters, while the h predominated when writing using Roman letters.

^Hamilton, John Noel (1974). A Phonetic Study of the Irish of Tory Island, County Donegal. Institute of Irish Studies, The Queen's University of Belfast.

^Lucas, Leslie W. (1979). Grammar of Ros Goill Irish, County Donegal. Institute of Irish Studies, The Queen's University of Belfast.

^William Gerard commented as follows: "All Englishe, and the most part with delight, even in Dublin, speak Irishe", while Richard Stanihurst lamented that "When their posteritie became not altogither so warie in keeping, as their ancestors were valiant in conquering, the Irish language was free dennized in the English Pale: this canker tooke such deep root, as the bodie that before was whole and sound, was by little and little festered, and in manner wholly putrified." See "Tony Crowley, "The Politics of Language in Ireland 1366-1922: A Sourcebook" and Leerssen, Joep, Mere Irish and Fior-Ghael: Studies in the Idea of Irish Nationality, Its Development and Literary Expression Prior to the Nineteenth Century, University of Notre Dame Press 1997, p. 51. ISBN 978-0268014278. There were still an appreciable number of Irish speakers in County Dublin at the time of the 1851 census: see Fitzgerald 1984.